Pressure switch



Jan. 28, 1964. D. T. MEISENHEIMER. JR., ETAL 3,

PRESSURE swncu Filed Oct. 2, 1959 2 Sheets-Sheet 1 F|G.1 H 34 INVENTORSDANIEL T. MEISENHEIMEFSIK LOUIS W. SYARTO Jan. 28; 196 D. T.MEISENHEIMER. JR.. ETAL 3,

PRESSURE SWITCH Filed Oct. 2, 1959 2 Sheets-Sheet 2 FIG. 3

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INVENTORS DANIEL T. MEISENHEIMERJR.

LOUIS w. SYARTO ATTORNEY United States Patent 0 3,119,919 PRESESURESWITCH Daniel T. Meisenheimer, .Ir., 50 Morris Lane, Milford,

Conn, and Louis W. Syarto, 184 Highlawn Road, Fairfield, Conn.

Filed 9st. 2, 1959 Ser. No. 84 %,899 13 Claims. (Cl. MIL-83) The presentinvention relates generally to fluid pressure switches and particularlyto shock resistant fluid pressure switches and mounting bracketstherefor.

The present invention contemplates improvements in fluid pressureswitches of the type which are actuated by a single reference fluidpressure. Switches of this type have been constructed having a diaphragmor piston movable by a reference pressure, the diaphragm or pistonmovement serving to actuate a small electrical switch. Such prior artdevices have also included means for adjusting the spring tension of acoil spring or similar member which resists the movement of the pistonor diaphragm, so that in effect, the actuation pressure of the switchmay be varied. Known prior art switches, however, have been somewhatlacking in their ability to withstand severe shocks or the applicationof G loads which in some modern aircraft or missile applications mayreach a value in excess of 25 GS.

The purpose of the present invention in its broader aspects is toprovide a fluid pressure switch of the type mentioned which is betterable to withstand severe shocks or G loads than prior devices of thistype. In keeping with this purpose, the present invention also providesin combination with the aforementioned switch, means for mounting theswitch to an aircraft or missile. This mounting means is particularlyable to isolate the switch elements from shock while the mount isspecifically designed to withstand high G loads without bending.

As a more specific aspect of the invention, a switch housing is providedhaving a principal member of rigid single piece construction, thismember being adapted to receive two end members whereby the housingenclosure is completed. A diaphragm responsive to a reference pressureis provided and is supported within one of the end members. The oppositeend member provides a mount for a small electrical switch which iscompletely enclosed within the housing. Intermediate the diaphragm is aswitch actuation mechanism, longitudinally movable by the diaphragm inone direction and urged in an opposite direction by spring means. Thepressure of the spring means acting against the actuation mechanism maybe varied by the translatory longitudinal movement of an adjustingmember. The adjusting member is threadably engaged with a control memberwhich when rotated, causes a corresponding translatory movement of theadjusting member. This latter movement reduces or increases the pressureof the spring means against the switch actuation mechanism, therebychanging the reference pressure required to actuate the switch. Theentire spring adjusting mechanism is enclosed within the aforementionedrigid single piece portion of the housing.

As a further and more specific aspect of the invention, the translatingspring adjusting member may be restrained from rotation and may beguided in its longitudinal translatory movement by a plurality of pinswhich are mounted to the housing. In one form of the invention, portionsof the switch actuating mechanism may be guided in their longitudinalmovement by a part of the spring adjusting mechanism, so that forcesacting upon the switch in a direction normal to its longitudinal axiswill be relatively unlikely to influence the longitudinal movement ofthe switch actuation mechanism.

Another feature of the invention lies in the construction of a novelswitch mounting bracket which contributes to the shock resistantproperties of the pressure switch. In its broader aspects, the mountingbracket is attached to the principal portion of the housing by means ofa single bolt. This bolt is substantially centrally located in themounting bracket and is insulated in its attachment thereto by beingembedded in a shock resistant material. The bracket also includes twolongitudinal arms which rest against widely spaced portions of thehousing. Each of the arms include shock absorbing members. The spacedarms are adapted to be clamped against the exterior of the housing whenthe mounting bolt is tightened in its mooring within the housing wall.Thus, the construction of the mounting bracket is such that there willbe no direct metal to metal connection between the switch and thebracket. The intervening shock absorbing material, therefore, acts toinsulate the switch from external vibration or shock. Also, the spacedarm construction provides a unique distortion-free design adapted toresist severe deflections, such as high G loads.

These and other specific aspects of the invention have been providedwhich will become more readily apparent after a detailed examination ofthe following description and the accompanying drawings in which:

FIG. 1 is an elevational View of a preferred embodi merit of a pressureswitch incorporating the present inventions shock resistant and anti-Gfeatures;

FIG. 2 is a top view of the embodiment of FIG. 1 disclosing morespecifically certain of the mounting provisions of the invention;

FIG. 3 is a cross sectional view taken along the lines 33 of FIG. 1; and

FIG. 4 is a cross-sectional View, similar to FIG. 3, but partiallybroken away, showing a modification according to the invention.

With reference to FIG. 3, a pressure switch 10 constructed according tothe present invention has been illustrated. Switch It) includes asubstantially hollow longitudinal body member "'12 of rigid single piececonstruction. At its upper end, body member 12' has been provided withinternal threads 14 which are adapted to engage in correspondingthreaded relationship with an externally threaded end member or plug 16.Plug 16 has been provided with an O-ring seal 17 so that when the parts12 and 16 are threaded together, a sealed closure of the upper end ofmember 12 will be effected. Plug 16 serves as a mount for a smallelectrical switch 18 which is attached to the underside thereof by meansof a bracket 2t and mounting screws 22. Switch is has been provided withterminals 24 and 26 which are connected externally of the switch housingto a suitable mechanism which is to be controlled by switch 18. Exteriorterminals 28, 349 and 32 provided for this purpose have been shown inFIG. 2. The upper end of a terminal post 34 has been threaded externallyso as to be adapted to engage with a mating electrical connector (notshown). A polyethylene cap 36 may also be provided, which serves as adust cover when the switch is not being used.

The lower end of the body member 12. is likewise provided internallywith a series of threads 38 which are adapted to engage withcorresponding external threads provided on a lower end plug 40. Bodymember 12 has been formed with an annular shoulder 42 against which aspacer 44 will abut when plug 46) has been brought into full threadedengagement with member 1 2. The outer periphery 46 of a diaphragm 48 isheld tightly between Washer 44 and plug 40. Plug it! has been providedwith an internally threaded port 5i) which may be connected to a fluidpressure line (not shown). By this means the reference pressure may actagainst the lower surface of a diaphragm 48, this pressure beingprevented from escaping between Washer 44 and plug 40 by means of a seal52.

Immediately above the diaphragm 48 and resting against its uppersurface, is a piston-like member 54 which is adapted to move in anupward longitudinal direction whenever the diaphragm is deflected by thereference pressure. The movement of piston 54 is transmitted to apushrod 56 whose upper end is in contact with an actuating button 58forming part of switch 18. A coil spring 66 hearing against an abutment61 of piston 54 urges piston 54 downwardly against diaphragm 4 8.Actuation of switch 18 is prevented until a certain specific referencepressure is exceeded, this pressure being determined by the exposeddiaphragm area, and the pressure of the spring. The design of the switchis such that it permits interchangeability of diaphragms havingdifferent areas or of diaphragms composed of different materials. Thus,a switch may be altered so that it will respond to pressures in widelydifferent ranges.

In order that the response of a switch within a given pressure range maybe adjusted or calibrated, the invention provides a means for varyingthe spring force exerted against the actuating piston 54. Situated abovepiston 54 body member 12 has been formed having a transverse integralwall section 62 which contributes to the rigidity of the switchconstruction. In addition, wall 62 serves as a mounting support for aplurality of longitudinally disposed pins 64. Pins 64 each have one endfastened within wall 62 so that the pins depend from wall 62 in adownward direction. Pins 64 serve to support a spring adjusting memberin the form of a collar 66 which is adapted to slide longitudinallythereon. The lower end of collar 66 abuts an upper portion of the spring66 and will therefore cause a greater or lesser compression of thespring depending upon the longitudinal position of collar 66 within thehousing. A control member 68 which is threadably engaged at 70 withcollar 66 may be rotated to cause longitudinal translation of collar 66.The control member 68 has an upper annular bearing surface 72 and alower annular bearing surface 74 which corresponds in diameter to theinternal diameter of body member 12, and the member 68 will thereby beguided in its rotation within body member 12 of the switch housing bythe bearing surfaces 72 and 74.

With reference to FIG. 1, it will be observed that two oppositelydisposed access windows or openings 76 have been provided in the bodymember 12. Furthermore, a portion of the control member 68 has beenprovided with grooves or teeth 77 which are accessible through theopenings 76. Teeth 77 may be engaged by a tool such as a screwdriver, inorder to cause rotation of the control member 63 and thus, adjustment ofspring 60. After the adjustment has been made, locking screws '78 maythen be tightened against teeth 77 of member 63 to prevent furthermovement thereof.

With reference to FIG. 3, collar 66has been provided with a centralopening 79, which is adapted to receive an intermediate portion ofpushrod 56. Collars 66 therefore assists in guiding pushrod 56 as it ismoved longitudinally toward or away from switch 18. A longitudinallyaligned passage 82 has also been provided in wall 62 to permit thepassage of the upper end of pushrod 56.

The operation of the pressure switch shown in FIGS. l-3 is as follows:

Port will be connected to a reference pressure which will act againstthe exposed lower surface of diaphragm 48. When the reference pressurehas achieved a high enough value, diaphragm ddwill be deflectedupwardly, thereby causing piston 54 to move pushrod 56 sufiiciently toactuate switch button 58 and switch 18. The effective pressure requiredto actuate the switch will depend upon the diaphragm area and upon theresisting pressure of spring 60. Resistance of spring may be varied inorder to change the actuation pressure of the switch. This isaccomplished by inserting a tool such as a screwdriver through one ofthe windows 76 provided within the body member 12 of the switch housingand by rotating the control member 68 to the right or to the left.Rotation of member 68 will cause collar 66- to translate upwardly ordownwardly along pins 64. The travel of collar 66 will cause greater orless compression of spring 60, thereby adjusting the actuation pressureof the switch;

FIG. 4 illustrates a modification according to the invention. In thisform a piston having an elongated upper section ill of cylindricalcross-section rests against the upper surface of diaphragm 112. Theelongated sec-' tion of the piston has a hollow bore 114 which isadapted to receive a pushrod 116 so that upward movement of the pistoncaused by deflection of the diaphragm will cause actuation of the switch118. The upper portion of the elongated section of the piston is adaptedto be received within a mating bore located Within a collar 1 20 so thatpiston 116 will be guided in its upward movement by means of the slidingfit between elongated section 111 and collar 12%. Collar abuts the upperend of a stack spring 121 whose lower end is retained by an annularshoulder T22 of the piston 11!). Collar 129 is supported by a pluralityof pins which restrain the collar from rotation but permit limitedtranslatory movement thereof in a downward or upward direction. As inthe embodiment of FIGS. 1-3, collar 12% is caused to translate in alongitudinal direction by means of a rotatable control member 139 whichis threadably engaged therewith. Thus, in the modification of FIG. 4,.the upper elongated section 111 of the piston lltl is slidably fittedwithin the spring adjusting collar 126 while the piston contributes tothe lateral support of the stack spring. This construction isparticularly adapted to Withstand transverse shocks because of themutual support provided by the various longitudinally movable elements.

in combination with the pressure switch just described, the inventionalso provides a novel shock nrount which is adapted to cooperate withthe structure of the switch in minimizing the effects of shock and/orhigh G loads upon the moving parts thereof. Accordingly, a singlemounting bolt 84 is threadably secured at one end to member 12 of theswitch housing. The other end of bolt passes through a resilient grommet86 which has shock absorbing qualities. Grommet 86 has been providedwith an annular groove 8 8 which is adapted to receive a portion of avibration isolator 92.

As is best seen in FIG. 2, vibration isolator 92 has been constructed toencircle approximately three quarters of the periphery of the switchhousing.

T wo shock-absorbent strips 94 and 96 are attached re spectively to theinner upper and lower edges of vibt aw tion isolator 92. The attachmentof these strips to the isolator may be made by the use of modernhigh-strength adhesives. Isolator 92 carrying strips 94- and 96, will bebrought up tightly against the switch housing by tightening bolt 84. Inan alternate construction (not shown) strips 94 and 96 may also bebonded to the exterior of the hensing, and provided that the bondingmaterial has suflicient strength, mounting bolt 84 nray be eliminatedentirely.-

The novel shock mount also includes a mounting bracket 97 which isattached to the vibration isolator 92 by means of bolts 93. Mountingbracket 97 has been provided with a dished-in area 99 having an opening11% therein, which gives access to the head of bolt 84. As will beobserved with reference to FIGURES 1 and 2, the mounting bracket 97 hasbeen formed to have a flat web portion 101 which is adapted to bemounted to a partition in an aircraft or missile. For this purposeattaching holes 102 and 103- hiave been provided. The upper and lowerlegs 1% and of the mounting bracket 97 have been constructed in the formof sheet metal arms which encircle approximately one-half of thevibration isolator. 92. Bolts 9i which attach mounting bracket 97 to thevibnation isolator 92 will be tightened sufficiently .to assure that topand bottom legs 104 and 105 of the mounting bracket will be clampedtightly about the periphery of vibration isolator 92.v

It will be observed that the combination of the vibration isolator 92and the mounting bracket 97 provides a shock mount which, though made ofsheet metal, has the strength of a casting. The arms of the vibrationisolator 92 bear against the exterior of the switch housing 12 at widelyspaced longitudinal points while the genenally cylindrical shape ofisolator 92 imparts great longitudinal rigidity to this member. Thecombination of the mounting bracket and isolator is such that therigidity of isolator 92 will prevent bending of legs Mid and 1% when theswitch is subjected to vertical loads. Furthermore, the legs 1634 andMP5 of mounting bracket 97 which encircle the vibration isolator 92 aredesigned specifically to resist lateral bending forces. Finally, thevibration isolator itself is so constructed that no directmetal-to-metal connection is made between the switch housing and thestructure to which it is mounted. lit has been found that a shockmountconstructed according to the invention is well able to resistdeflections in excess of twenty-five Gs.

Thus, it will be seen that the present invention provides a pressureswitch having a housing of substantially singlepiece construction, therigidity of the housing contributing substantially to theshock-resistance properties of the switchactuating elements enclosedtherein. in combination with the switch the invention also provides aunique shock-resistant mount which is adapted to isolate the switch fromvibrations which otherwise might be transmitted from the structure towhich it is mounted. While providing vibration isolation, theconstruction of the shock mount is such that it can resist deflectionsfrom extremely highlongitudinal and transverse forces.

It will be appreciated that the invention though described in connectionwith a. pressure switch may actually assume the form of a pressureactuator for devices other than switches. In this broader form, thenovel pressure responsive structure disclosed may be employed to actuatea potentiometer, a linear variable differential transformer, or othersuitable devices. It should therefore be understood that the foregoingdescription is directed to a preferred embodiment of the invention andis representative only. Various departures from what has been shown anddescribed may be made within the spirit and scope of the invention asmore particularly defined in the appended claims.

We claim:

1. In a fluid pressure switch of the type having a housing, a port atone end of said housing adapted to be connected to reference pressure,pressure responsive means movable by said pressure, the movement of saidpressure responsive means being transmitted in one directionlongitudinally of said housing to a switch actuator, resilient meansurging said actuator in an opposite direction, a switch adapted to beactuated by said switch actuator, and adjusting means acting upon saidresilient means for adjusting the resiliency thereof, the improvementcomprising a housing for said fluid pressure switch including agenerally longitudinally disposed body member of rigid single-piececonstruction, said longitudinally disposed body meiiber being providedwith an access opening, said housing also including two end membersattached to said longitudinal body member in sealed relation, a firstone of said end members defining said reference pressure port andproviding structural support for said pressure responsive means, asecond one of said end members providing support for said switch, saidadjusting means comprising a collar, control means being threadablyengaged with said adjusting means such that rotation of said controlmeans causes translatory movement of said collar and adjustment of saidresilient means, guide means within said housing to support saidadjusting means and accommodating longitudinal adjusting movementthereof, said control means being mounted within said housing and in asurrounding relation to said adjusting means, said control meanscooperating with said adjusting means for causing longitudinal movementthereof, said guide means acting to restrain said collar v6 fromrotation when said control means is rotated, and sealing meansassociated with said control means and said housing serving to isolatesaid adjusting means from said access opening.

2. In a fluid pressure switch of the type having a hous ing, a port atone end of said housing adapted to be connected to a reference pressure,pressure responsive means movable by said pressure, the movement of saidpressure responsive means being transmitted in one directionlongitudinally of said housing to a switch actuator, resilient meansurging said actuator in an opposite direction, a switch adapted to beactuated by said switch actuator, and adjusting means acting upon saidresilient cans for adjusting the resiliency thereof, the improvementcomprising a housing for said fluid pressure switch including agenerally longitudinally disposed body member of rigid single-piececonstruction, said longitudinally disposed body member being providedwith an access opening, said housing also including two end membersattached to said longitudinal body member in sealed relation, a firstone of said end members defining said reference pressure port andproviding structural support for said pressure responsive means, asecond one of said end members providing support for said switch, guidemeans within said housing supporting said adjusting means andaccommodating longitudinal adjusting movement thereof, control meansbeing mounted within said housing and in surrounding relation to saidadjusting means, said control means cooperating with said adjustingmeans for causing longitudinal movement thereof, said adjusting meanscomprising a collar and said control means being threadably engaged withsaid adjusting means such that rotation of said control means causestranslatory movement of said collar and adjustment of said resilientmeans, said collar being supported by said guide means, said guide meanscomprising a plurality of longitudinally disposed pin leans mounted tosaid housing, said pin means acting to restrain said collar fromrotation when said control means is rotated, and sealing meansassociated with said control means and said housing and serving toisolate said adjusting means from said access opening.

3. A pressure switch according to claim 1 wherein said resilient meanscomprises a spring and said switch actuator includes a push-rod, one endof said push-rod is in contact with said pressure responsive means, theother end of said push-rod is adapted to cause actuation of said switch.

4. The combination of a fluid pressure switch and a shock mount, saidfluid pressure switch comprising a housing, means forming a port at oneend of said housing adapted to be connected to a reference pressure,diaphragm means movable in response to said pressure, said diaphragmmovement being transmitted in one direction longitudinally of saidhousing to a switch actuator, spring means urging said actuator in anopposite direction, a switch adapted to be actuated by said switchactuator, means acting upon said spring means for adjusting thecompression of said spring means, said housing including a generallylongitudinally disposed body member of rigid single-piece constructionhaving a transverse wall integral therewith, said housing also includingtwo end members enclosed by and attached to said longitudinal bodymember, one of said end members defining said reference pres,- sure portand providing structural support for said diaphragm, the other of saidend members providing support for said switch, guide means within saidhousing supporting said spring adjusting means and adapted to permitlongitudinal movement thereof, said switch actuator including alongitudinally slidable piston and a pushrod, one end of said pistonbeing in direct physical contact with said diaphragm, the other end ofsaid piston acting upon said push-rod adapted to cause actuation of saidswitch, said spring means comprising a coil spring, said springadjusting means comprising a collar acting upon and adjusting thecompression of said coil spring,

rotatable control means threadably engaged with said collar for causinglongitudinal movement thereof, said collar adapted for longitudinalmovement within said housing, said collar abutting one end of saidspring, said guide means comprising a plurality of longitudinallydisposed guide pins mounted on said transverse housing wall andsupporting said collar, said guide pins acting to restrain said collarfrom rotation such that rotation of said control means causeslongitudinal movement of said collar thereby adjusting the tension ofsaid spring, said longitudinal body member having an opening in itsexterior wall providing access to said rotatable control means wherebysaid spring may be adjusted from a position exterior to said housing;and a shock mount comprising a mounting pin having one end adapted to bethreadably mounted within a portion of the switch housing, the op positeend of said mounting pin being embedded in and afiixed to a shockabsorbing grommet, means for affixing said grommet to a vibrationisolator, said isolator having two longitudinally spaced arms adapted toencircie and rest against the switch housing, said arms including shockabsorption means, the mounting pin, grommet and isolator beingconstructed such that threading of the mounting pin into the switchhousing will cause said mounting pin to clamp the spaced arms or" saidisolator against the exterior of said housing, a mounting bracket havingupper and lower legs adapted to rest against said isolator, andattaching means for aflixing said mounting bracket to said vibrationisolator, said attaching means being adapted to clamp said mountingbracket tightly against said vibration isolator.

5. A shock mount for a switch or the like comprising a mounting pinhaving one end adapted to be fastened to a housing for said switch, theother end of said pin being affixed to a vibration isolator andinsulated therefrom by an intermediate shock absorbing grommet, saidisolator being adapted to rest against the exterior of said housing atspaced points, said isolator including shock absorbing means at saidpoints, said mounting pin being adapted to cause said isolator to beclamped against said housing, and a mounting bracket having upper andlower legs adapted to rest against said isolator, attaching means foraffixing said mounting bracket to said vibration isolator, saidattaching means being adapted to clamp said mounting bracket tightlyagainst said vibration isolator.

6. A pressure switch according to claim 5 wherein thevibration isolatoris of substantially arcuate shape having 'two longitudinally spaced armsadapted to substantially encircle the switch housing, and said mountingbracket legs substantially encircle said isolator.

7. A shock mount for a switch housing or the like comprising a vibrationisolator and a mounting bracket for said isolator, said isolator beingconstructed such that it will contact said switch housing at a pluralityof widely spaced points, said points of contact including shockofshock-absorbent material which are adapted to contact the switchhousing, said strips forming a part of said vibration isolator, andwherein the means for attaching the isolator to the switch housingcomprises a bonding adhesive.

t? 9. A shock mount according to claim 7 wherein the means for attachingthe vibration isolator to the switch housing comprises a mounting boltwhich is threadably connected to the structure of the vibration isolatorby means of a resilient shock-absorbent material.

10. A sheet metal shock mount for a switch housing or the likecomprising a mounting bracket adapted to be fastened to fixed structureand an intermediate member adapted to be attached to said housing, saidmounting bracket having a back and upper and lower legs generallyperpendicular to said back, said legs defining a cutout against whichupper and lower portions of said intermediate memher are adapted tonest, said intermediate member being constructed of a shape such that itoffers great resistance to horizontal bending movements, and means forattaching said intermediate member to said mounting bracket.

11. A mount according to claim 10 wherein said intermediate member is ofgenerally cylindrical shape and substantially encircles said housing.

12. A mount according to claim 10 wherein said intermediate memberincludes shock-absorbing means at those parts of said member whichcontact the housing.

13. A fluid pressure actuated assembly comprising a unitary, rigid bodyof generally tubular form, an actuated device mounted in sealed relationat one end of said body and having a movable element exposed to theinterior of the body, means closing the other end of said tubular bodyin sealed relation and forming a pressure fluid port ."for connection toa source of pressure fluid, means within sive element exposed withinsaid chamber, connecting means extending longitudinally through theinterior of said tubular body and connecting said pressure responsiveelement with the movable element of said actuated device, a returnspring located within said tubular body and acting longitudinally uponsaid pressure responsive element in opposition to said pressure fluid, aspring adjusting member received within said tubular body and actinglongitudinally upon one end of said spring, means for guiding saidspring adjusting member for longitudinal adjusting movement within saidbody, said tubular body having an access opening in a side wall portionthereof, a rotatable control member received within said tubular body ingenerally surrounding relation to said return spring and said springadjusting member, said control member being accessible for rotationthrough said access opening and being operatively connected to saidspring adjusting member to effect longitudinal movement thereof inaccordance with rotation of the control member, and annular sealingmeans acting between said control member and interior walls of saidtubular body on opposite sides of said access opening to seal theinterior of said tubular body and the mechanism housed therein.

References tilted in the file of this patent UNITED STATES PATENTS1,938,327 Green Dec. 5, 1933 2,182,450 Clarkson Dec. 5, 1939 2,638,303Pietz May 12, 1953 2,742,544 Lovick Apr. 17, 1956 2,756,016 Panter July24, 1956 2,789,176 Mercier Apr. 6, 1957 2,890,305 Gutkowski June 9, 19592,917,264 Hartenstein Dec. 15, 1959 2,919,882 Barkalow Jan. 5, 19602,924,420 Fink Feb. 9, 1960

2. IN A FLUID PRESSURE SWITCH OF THE TYPE HAVING A HOUSING, A PORT ATONE END OF SAID HOUSING ADAPTED TO BE CONNECTED TO A REFERENCE PRESSURE,PRESSURE RESPONSIVE MEANS MOVABLE BY SAID PRESSURE, THE MOVEMENT OF SAIDPRESSURE RESPONSIVE MEANS BEING TRANSMITTED IN ONE DIRECTIONLONGITUDINALLY OF SAID HOUSING TO A SWITCH ACTUATOR, RESILIENT MEANSURGING SAID ACTUATOR IN AN OPPOSITE DIRECTION, A SWITCH ADAPTED TO BEACTUATED BY SAID SWITCH ACTUATOR, AND ADJUSTING MEANS ACTING UPON SAIDRESILIENT MEANS FOR ADJUSTING THE RESILIENCY THEREOF, THE IMPROVEMENTCOMPRISING A HOUSING FOR SAID FLUID PRESSURE SWITCH INCLUDING AGENERALLY LONGITUDINALLY DISPOSED BODY MEMBER OF RIGID SINGLE-PIECECONSTRUCTION, SAID LONGITUDINALLY DISPOSED BODY MEMBER BEING PROVIDEDWITH AN ACCESS OPENING, SAID HOUSING ALSO INCLUDING TWO END MEMBERSATTACHED TO SAID LONGITUDINAL BODY MEMBER IN SEALED RELATION, A FIRSTONE OF SAID END MEMBERS DEFINING SAID REFERENCE PRESSURE PORT ANDPROVIDING STRUCTURAL SUPPORT FOR SAID PRESSURE RESPONSIVE MEANS, ASECOND ONE OF SAID END MEMBERS PROVIDING SUPPORT FOR SAID SWITCH, GUIDEMEANS WITHIN SAID HOUSING SUPPORTING SAID ADJUSTING MEANS ANDACCOMMODATING LONGITUDINAL ADJUSTING MOVEMENT THEREOF, CONTROL MEANSBEING MOUNTED WITHIN SAID HOUSING AND IN SURROUNDING RELATION TO SAIDADJUSTING MEANS, SAID CONTROL MEANS COOPERATING WITH SAID ADJUSTINGMEANS FOR CAUSING LONGITUDINAL MOVEMENT THEREOF, SAID ADJUSTING MEANSCOMPRISING A COLLAR AND SAID CONTROL MEANS BEING THREADABLY